There are 10 standardized Medicare Supplement plans, each identified by a letter. The plans with the most comprehensive coverage and the highest premiums are Plans F and G. 

The most popular Medicare Supplement plan is Plan F. It covers the Medicare Part A deductible, coinsurance, and copayments; the Part B deductible; blood; and foreign travel emergency care. 

Plan G is very similar to Plan F, but it does not cover the Part B deductible. 

Other popular Medicare Supplement plans include Plan C, which covers most of what Plans F and G cover except for foreign travel emergency care; and Plan D, which has slightly lower premiums than Plan C but higher out-of-pocket costs.

Questions to Ask When Shopping for Coverage

There are a lot of different Medicare Supplement Insurance companies out there, so how do you know which one is right for you? Here are some important questions to ask when shopping for coverage:

1. What is the company's financial stability? You want to make sure that the company you choose is financially stable and will be able to pay out claims in the event that you need to use your policy.

2. What is the company's customer service like? You'll want to choose a company that has good customer service and is easy to work with.

3. What kind of coverage does the company offer? Make sure that the company you choose offers the type of coverage you need.

4. How much does the coverage cost? Be sure to compare prices between different companies before making a decision.

5. Is there anything else I should know about the company? Ask around and do some research to see if there are any red flags or negative reviews about the company you're considering.